Q.yellow leaves dropping/spider webs on new shoots causing death – Mandevilla plant
This year, I bot a new Mandevilla plant from another nursery, and it is developing the same problems. Leaves turn yellow seemingly overnight, and either drop off of I remove them. There also now appears spinder-like webbing on the few new shoots which have caused the new growth to blacken and shrivel. Plant probably got too much water with all the rain we’ve had in CT, so took its saucer away. Also looks like little white dots on the underside of one leaf.
Any way to stop the death of this expensive plant?
Yellowing leaves can indicate pests as well as watering issues.
With the addition of webbing, your plant likely has Spider Mites.
Treat the plant with Neem Oil.
These links will help you.